Source: Extra Practice
In a Vernier Calliper, 10 divisions of Vernier scale coincide with 9 divisions of main scale. If 1 Main Scale Division (MSD) is 1 mm, the least count is:
Options
Option A is correct
0.1 mm
Option B
0.01 mm
Option C
1 mm
Option D
0.9 mm
Explanation
Least Count = 1 MSD - 1 VSD. Given 10 VSD = 9 MSD, so 1 VSD = 0.9 MSD. LC = 1 MSD - 0.9 MSD = 0.1 MSD. Since 1 MSD = 1 mm, LC = 0.1 mm. 0.01 mm is typical for screw gauges. 1 mm is the MSD value. 0.9 mm is the value of one VSD, not the least count.